Meera Gupta - Academia.edu (original) (raw)

Papers by Meera Gupta

Abstract: A minimum between solar cycle 22 and 23 has been defined earlier on the basis of type-I... more Abstract: A minimum between solar cycle 22 and 23 has been defined earlier on the basis of type-I radio burst only. In the present paper a re-visit to the occurrence of type-I radio bursts in relation to general level of solar activity (sunspot number) is made covering the minima ...

Physical Review E, 2001

The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau... more The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau(ch)/tau(d) has been studied where tau(ch) and tau(d) are the dust charging and dust hydrodynamical time scales on the nonlinear propagation of dust acoustic waves. Analytical investigation shows that the propagation of a small amplitude wave is governed by a Korteweg-de Vries (KdV) Burger equation. Notwithstanding the soliton decay, the "soliton mass" is conserved, but the dissipative term leads to the development of a noise tail. Nonadiabaticity generated dissipative effect causes the generation of a dust acoustic shock wave having oscillatory behavior on the downstream side. Numerical investigations reveal that the propagation of a large amplitude dust acoustic shock wave with dust density enhancement may occur only for Mach numbers lying between a minimum and a maximum value whose dependence on the dusty plasma parameters is presented.

Abstract A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with c... more Abstract A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with cosmic ray intensity (CRI) in the neutron monitor energy range has been performed for the solar cycles 21, 22 and 23. It is found that solar activity parameters (SSN and TA) are ...

We have performed a correlative analysis of solar activity (Sunspot numbers and Tilt Angle) with ... more We have performed a correlative analysis of solar activity (Sunspot numbers and Tilt Angle) with cosmic ray intensity (CRI) observed by the neutron monitor stations having different cut-off rigidity for the period 1976 to 2014 covering the solar cycles 21, 22, 23 and present solar cycle 24. It is found that tilt angle (TA) and sunspot numbers (SSN) are highly correlated with each other and have inverse correlation with CRI during the entire period of investigation. We have also calculated "running cross correlation coefficient" between TA & CRI and observed that the correlation is unusually positive during the maxima of odd cycles 21 and 23. The 22-year solar cycle variational pattern is clearly apparent in the different types of analysis based on Tilt Angle observations. It has been noticed that the behaviour of cycle 23 in declining phase is different than cycle 21 & 22 and tilt angle does not coincides with the sunspot activity during the minima of present solar cycle 2...

Major solar flare events have been selected to study the heliographic distribution of solar flare... more Major solar flare events have been selected to study the heliographic distribution of solar flares during solar cycle 23. The occurrence of Forbush decreases (FDs), bright solar flares; solar flare index, coronal mass ejections (CMEs), average solar magnetic field and solar wind velocity have been studied for the period 1996-2006. It is found that the solar flare index in northern and southern hemisphere represents the cumulative activity of solar flare in both hemispheres. Though, the bright solar flares are equally distributed in the entire solar region, majority of the bright solar flares responsible for FDs (≥ 4% magnitude) are located in the north-east region of the solar disk. Out of 41 FDs, 88% are found to be associated with halo (central position angle ≈ 360°) and partial halo (central position angles ≥ 120°) CMEs (coronal mass ejections) and 55% with bright solar flares of importance ≥ 1B. The abrupt increase in average solar magnetic field and solar wind velocity has also been found to be a necessary condition for producing FDs. The occurrence of non-recurrent type FDs are more frequent than recurrent type FDs. In latitudinal distribution, northern hemisphere is more dominant than the southern hemisphere in producing FDs. It is also found that eastern hemisphere is more effective as compared to western hemisphere to produce FDs in longitudinal distribution during the aforesaid period.

PLoS ONE, 2014

Respiratory syncytial virus (RSV) and human Metapneumovirus (hMPV), viruses belonging to the fami... more Respiratory syncytial virus (RSV) and human Metapneumovirus (hMPV), viruses belonging to the family Paramyxoviridae, are the most important causes of lower respiratory tract infection in young children. Infections with RSV and hMPV are clinically indistinguishable, and both RSV and hMPV infection have been associated with aberrant adaptive immune responses. Myeloid Dendritic cells (mDCs) play a pivotal role in shaping adaptive immune responses during infection; however, few studies have examined how interactions of RSV and hMPV with individual mDC subsets (BDCA-1 + and BDCA-3 + mDCs) affect the outcome of anti-viral responses. To determine whether RSV and hMPV induce virus-specific responses from each subset, we examined co-stimulatory molecules and cytokines expressed by BDCA-1 + and BDCA-3 + mDCs isolated from peripheral blood after infection with hMPV and RSV, and examined their ability to stimulate T cell proliferation and differentiation. Our data show that RSV and hMPV induce virus-specific and subset-specific patterns of co-stimulatory molecule and cytokine expression. RSV, but not hMPV, impaired the capacity of infected mDCs to stimulate T cell proliferation. Whereas hMPVinfected BDCA-1 + and BDCA-3 + mDCs induced expansion of Th17 cells, in response to RSV, BDCA-1 + mDCs induced expansion of Th1 cells and BDCA-3 + mDCs induced expansion of Th2 cells and Tregs. These results demonstrate a virusspecific and subset-specific effect of RSV and hMPV infection on mDC function, suggesting that these viruses may induce different adaptive immune responses.

Transplant Infectious Disease, 2009

Purpose. Gram-positive (GP) organisms are among the most common cause of infections in early post... more Purpose. Gram-positive (GP) organisms are among the most common cause of infections in early postsurgical and immunocompromised populations. Patients recovering from lung transplantation (LT) are particularly susceptible owing to the physiologic stress imposed by surgery and induction with intense immunosuppression. Sites, types, and timing of GP infections following LT are not well documented.This report describes the clinical spectrum of GP infections and their e¡ects on surgical airway complications (SAC) and bronchiolitis obliterans syndrome (BOS) following LT. Methods and materials. Data were collected from 202 patients undergoing 208 LT procedures at a single institution between November 1990 and November 2005. Data were retrospectively analyzed according to timing, location, and causative pathogen. Results. In the median follow-up period of 2.7 years (range, 0^13.6 years), 137 GP infections were con¢rmed in 72 patients. Sites of infection included respiratory tract (42%), blood (27%), skin, wound and catheter (21%), and other (10%). GP pathogens identi¢ed were Staphylococcus species (77%), Enterococcus species (12%), Streptococcus species (6%), Pneumococcus (4%), and Eubacterium lentum (1%). The likelihood of SAC and BOS was increased in lung allograft recipients with GP pneumonia as compared with those without (hazard ratio 2.1; 95% con¢dence interval 5 1.5^3.1). Conclusions. GP organisms were responsible for infections in 40% of lung allograft recipients and most commonly isolated from the respiratory tract and blood stream. Staphylococcal species were most frequently identi¢ed, 42% of which were methicillin-resistant Staphylococcus aureus (MRSA). Given the strong association of respiratory tract infections with the development of SAC and BOS, empiric antimicrobial strategies after LTshould include agents directed against GP organisms, especially MRSA.

Transplant Infectious Disease, 2008

Purpose. Clostridium di⁄cile colitis (CDC) is the most common nosocomial infection of the gastroi... more Purpose. Clostridium di⁄cile colitis (CDC) is the most common nosocomial infection of the gastrointestinal tract in patients with recent antibiotic use or hospitalization. Lung transplant recipients receive aggressive antimicrobial therapy postoperatively for treatment and prophylaxis of respiratory infections. This report describes the epidemiology of CDC in lung recipients from a single center and explores possible associations with bronchiolitis obliterans syndrome (BOS), a surrogate marker of chronic rejection. Methods. Patients were divided into those with con¢rmed disease (CDC 1 ) and those without disease (CDC À ) based on positive C. di⁄cile toxin assay. Because of a bimodal distribution in the time to develop CDC, the early postoperative CDC 1 group was analyzed separately from the late postoperative CDC 1 cohort with respect to BOS development. Results. Between 1990 and 2005, 202 consecutive patients underwent 208 lung transplantation procedures. Of these, 15 lung recipients developed 23 episodes of CDC with a median follow-up period of 2.7 years (range, 0^13.6). All patients with con¢rmed disease had at least 1 of the following 3 risk factors: recent antibiotic use, recent hospitalization, or augmentation of steroid dosage. Of the early CDC 1 patients, 100% developed BOS, but only 52% of the late CDC 1 patients developed BOS, either preceding or following infection. Conclusion. CDC developed in 7.4% of lung transplant patients with identi¢ed risk factors, yielding a cumulative incidence of 14.7%. The statistical association of BOS development in early CDC 1 patients suggests a relationship between early infections and future chronic lung rejection.

Solar Physics, 2006

Abstract From the monthly data of cosmic ray intensity (CRI), sunspot numbers (SSN) and solar fla... more Abstract From the monthly data of cosmic ray intensity (CRI), sunspot numbers (SSN) and solar flare index (SFI), an attempt has been made to study the relationship between CRI and solar activity (SA) parameters SSN and SFI. The correlation between SA parameters and ...

Physics of Plasmas, 2006

In modern technological applications electronegative dusty plasmas are widely used in semiconduct... more In modern technological applications electronegative dusty plasmas are widely used in semiconductor materials processing, in development of novel nanomaterials, etc. The dust grains produced by the chemical reaction in gas or plasma-surface interaction in such plasmas can ...

Physics of Plasmas, 2006

... 45, 449 (1997). GLDelzanno and G.Lapenta, “Modified Jeans Instability for Dust Grains in a Pl... more ... 45, 449 (1997). GLDelzanno and G.Lapenta, “Modified Jeans Instability for Dust Grains in a Plasma,” Phys. Rev. Lett. ... Permanent address: Department of Mathematics, Bengal Institute of Technology, Post-Hadia, Kolkata-700150, India. Electronic mail: banamaliroy@yahoo.co.in. ...

Physics of Plasmas, 2004

The effects of nonthermal ions with excess of fast (energetic) ions on linear dust acoustic (DA) ... more The effects of nonthermal ions with excess of fast (energetic) ions on linear dust acoustic (DA) wave propagation has been investigated incorporating the dust charge variation and the isothermal dust pressure variation. It is seen that due to the dust charge variations in the ...

Physics of Plasmas, 2004

The effect of secondary electron emission on dust acoustic wave (DA) propagation has been investi... more The effect of secondary electron emission on dust acoustic wave (DA) propagation has been investigated based on orbit motion limited theory of dust grain charging. The emitted secondaries are assumed to have the same temperature as that of the ambient plasma electrons so ...

Physics of Plasmas, 2010

The effect of magnetic field on the nonlinear growth rate of Rayleigh -Taylor instability induced... more The effect of magnetic field on the nonlinear growth rate of Rayleigh -Taylor instability induced two fluid interfacial structures has been investigated. The magnetic field is assumed to be parallel to the plane of the two fluid interface and acts in a direction perpendicular to the wave vector. If magnetic field is restricted only to either side of the interface the growth rate may be depressed (may almost disappear) or be enhanced depending on whether the magnetic pressure on the interface opposes the instability driving pressure difference g(ρ h − ρ l )y or acts in the same direction. If magnetic field is present on both sides of the two fluid interface, stabilization *

Physics of Plasmas, 2009

The effect of compressibility and of density variation on Rayleigh–Taylor and Richtmyer–Meshkov i... more The effect of compressibility and of density variation on Rayleigh–Taylor and Richtmyer–Meshkov instability of the temporal development of two fluid interfacial structures such as bubbles and spikes have been investigated. It is seen that the velocity of the tip of the bubble or spike ...

Physics of Plasmas, 2011

The combined effect of viscosity and vorticity on the growth rate of the bubble associated with s... more The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh -Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it. *

Physics Letters A, 2007

The effect of secondary electron emission on dust ion acoustic wave (DIA) propagation has been in... more The effect of secondary electron emission on dust ion acoustic wave (DIA) propagation has been investigated based on orbit motion limited (OML) theory of dust grain charging. The emitted secondaries are assumed to have the same temperature of that of the ambient plasma electrons so that the plasma is effectively composed of three components: The ions, electrons and the varying

Physics Letters A, 2000

The effects of nonadiabatic dust charge variation on nonlinear dust ion acoustic waves in collisi... more The effects of nonadiabatic dust charge variation on nonlinear dust ion acoustic waves in collisionless dusty plasma have been studied. Nonadiabaticity generated dissipative effect is found to cause generation of dust ion acoustic shock wave Ž . governed by the Korteweg-de Vries KdV Burger equation. Numerical integration of KdV Burger equation shows that it Ž . Ž . has either oscillatory dispersion dominant case or quasi-monotone dissipation dominant case shock wave solutions. q 2000 Published by Elsevier Science B.V. ) Corresponding 0375-9601r00r$ -see front matter q 2000 Published by Elsevier Science B.V.

Physics Letters A, 2002

Small but finite amplitude nonlinear acoustic mode at high dust density, i.e., the nonlinear dust... more Small but finite amplitude nonlinear acoustic mode at high dust density, i.e., the nonlinear dust electro acoustic (DEA) wave mode has been studied by reductive perturbation technique. The effect of dispersion is introduced to saturate the nonlinear steepening effect leading to Korteweg-de Vries (KdV) equation for the description of its propagation. It is found that the dispersive effect of DEA wave is more pronounced than that of dust acoustic (DA) wave for hydrogen plasma with equal electron, ion temperatures T e and T i . For lower values of T i /T e , the DEA soliton flattens out more and more as the dust space charge density |q d n d | increases but after maximum flattening the soliton width decreases and the soliton becomes more sharply peaked as |q d n d | comes closer to that of ions. In this respect and also in respect of soliton amplitude the behaviours of the DEA wave and DA wave differ qualitatively.  2002 Elsevier Science B.V. All rights reserved. 0375-9601/02/$ -see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 5 -9 6 0 1 ( 0 2 ) 0 0 1 9 3 -7

Physica Scripta, 2005

... It is seen that a DIA wave becomes unstable when the ionization rate sufficiently exceeds the... more ... It is seen that a DIA wave becomes unstable when the ionization rate sufficiently exceeds the recombination rate. This is also possible in absence of secondary electron emission. ... Page 4. 300 MR Gupta, Susmita Sarkar, Banamali Roy, Anupam Karmakar and Manoranjan Khan ...

Abstract: A minimum between solar cycle 22 and 23 has been defined earlier on the basis of type-I... more Abstract: A minimum between solar cycle 22 and 23 has been defined earlier on the basis of type-I radio burst only. In the present paper a re-visit to the occurrence of type-I radio bursts in relation to general level of solar activity (sunspot number) is made covering the minima ...

Physical Review E, 2001

The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau... more The effect of nonadiabaticity of dust charge variation arising due to small nonzero values of tau(ch)/tau(d) has been studied where tau(ch) and tau(d) are the dust charging and dust hydrodynamical time scales on the nonlinear propagation of dust acoustic waves. Analytical investigation shows that the propagation of a small amplitude wave is governed by a Korteweg-de Vries (KdV) Burger equation. Notwithstanding the soliton decay, the "soliton mass" is conserved, but the dissipative term leads to the development of a noise tail. Nonadiabaticity generated dissipative effect causes the generation of a dust acoustic shock wave having oscillatory behavior on the downstream side. Numerical investigations reveal that the propagation of a large amplitude dust acoustic shock wave with dust density enhancement may occur only for Mach numbers lying between a minimum and a maximum value whose dependence on the dusty plasma parameters is presented.

Abstract A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with c... more Abstract A detailed correlative analysis between sunspot numbers (SSN) and tilt angle (TA) with cosmic ray intensity (CRI) in the neutron monitor energy range has been performed for the solar cycles 21, 22 and 23. It is found that solar activity parameters (SSN and TA) are ...

We have performed a correlative analysis of solar activity (Sunspot numbers and Tilt Angle) with ... more We have performed a correlative analysis of solar activity (Sunspot numbers and Tilt Angle) with cosmic ray intensity (CRI) observed by the neutron monitor stations having different cut-off rigidity for the period 1976 to 2014 covering the solar cycles 21, 22, 23 and present solar cycle 24. It is found that tilt angle (TA) and sunspot numbers (SSN) are highly correlated with each other and have inverse correlation with CRI during the entire period of investigation. We have also calculated "running cross correlation coefficient" between TA & CRI and observed that the correlation is unusually positive during the maxima of odd cycles 21 and 23. The 22-year solar cycle variational pattern is clearly apparent in the different types of analysis based on Tilt Angle observations. It has been noticed that the behaviour of cycle 23 in declining phase is different than cycle 21 & 22 and tilt angle does not coincides with the sunspot activity during the minima of present solar cycle 2...

Major solar flare events have been selected to study the heliographic distribution of solar flare... more Major solar flare events have been selected to study the heliographic distribution of solar flares during solar cycle 23. The occurrence of Forbush decreases (FDs), bright solar flares; solar flare index, coronal mass ejections (CMEs), average solar magnetic field and solar wind velocity have been studied for the period 1996-2006. It is found that the solar flare index in northern and southern hemisphere represents the cumulative activity of solar flare in both hemispheres. Though, the bright solar flares are equally distributed in the entire solar region, majority of the bright solar flares responsible for FDs (≥ 4% magnitude) are located in the north-east region of the solar disk. Out of 41 FDs, 88% are found to be associated with halo (central position angle ≈ 360°) and partial halo (central position angles ≥ 120°) CMEs (coronal mass ejections) and 55% with bright solar flares of importance ≥ 1B. The abrupt increase in average solar magnetic field and solar wind velocity has also been found to be a necessary condition for producing FDs. The occurrence of non-recurrent type FDs are more frequent than recurrent type FDs. In latitudinal distribution, northern hemisphere is more dominant than the southern hemisphere in producing FDs. It is also found that eastern hemisphere is more effective as compared to western hemisphere to produce FDs in longitudinal distribution during the aforesaid period.

PLoS ONE, 2014

Respiratory syncytial virus (RSV) and human Metapneumovirus (hMPV), viruses belonging to the fami... more Respiratory syncytial virus (RSV) and human Metapneumovirus (hMPV), viruses belonging to the family Paramyxoviridae, are the most important causes of lower respiratory tract infection in young children. Infections with RSV and hMPV are clinically indistinguishable, and both RSV and hMPV infection have been associated with aberrant adaptive immune responses. Myeloid Dendritic cells (mDCs) play a pivotal role in shaping adaptive immune responses during infection; however, few studies have examined how interactions of RSV and hMPV with individual mDC subsets (BDCA-1 + and BDCA-3 + mDCs) affect the outcome of anti-viral responses. To determine whether RSV and hMPV induce virus-specific responses from each subset, we examined co-stimulatory molecules and cytokines expressed by BDCA-1 + and BDCA-3 + mDCs isolated from peripheral blood after infection with hMPV and RSV, and examined their ability to stimulate T cell proliferation and differentiation. Our data show that RSV and hMPV induce virus-specific and subset-specific patterns of co-stimulatory molecule and cytokine expression. RSV, but not hMPV, impaired the capacity of infected mDCs to stimulate T cell proliferation. Whereas hMPVinfected BDCA-1 + and BDCA-3 + mDCs induced expansion of Th17 cells, in response to RSV, BDCA-1 + mDCs induced expansion of Th1 cells and BDCA-3 + mDCs induced expansion of Th2 cells and Tregs. These results demonstrate a virusspecific and subset-specific effect of RSV and hMPV infection on mDC function, suggesting that these viruses may induce different adaptive immune responses.

Transplant Infectious Disease, 2009

Purpose. Gram-positive (GP) organisms are among the most common cause of infections in early post... more Purpose. Gram-positive (GP) organisms are among the most common cause of infections in early postsurgical and immunocompromised populations. Patients recovering from lung transplantation (LT) are particularly susceptible owing to the physiologic stress imposed by surgery and induction with intense immunosuppression. Sites, types, and timing of GP infections following LT are not well documented.This report describes the clinical spectrum of GP infections and their e¡ects on surgical airway complications (SAC) and bronchiolitis obliterans syndrome (BOS) following LT. Methods and materials. Data were collected from 202 patients undergoing 208 LT procedures at a single institution between November 1990 and November 2005. Data were retrospectively analyzed according to timing, location, and causative pathogen. Results. In the median follow-up period of 2.7 years (range, 0^13.6 years), 137 GP infections were con¢rmed in 72 patients. Sites of infection included respiratory tract (42%), blood (27%), skin, wound and catheter (21%), and other (10%). GP pathogens identi¢ed were Staphylococcus species (77%), Enterococcus species (12%), Streptococcus species (6%), Pneumococcus (4%), and Eubacterium lentum (1%). The likelihood of SAC and BOS was increased in lung allograft recipients with GP pneumonia as compared with those without (hazard ratio 2.1; 95% con¢dence interval 5 1.5^3.1). Conclusions. GP organisms were responsible for infections in 40% of lung allograft recipients and most commonly isolated from the respiratory tract and blood stream. Staphylococcal species were most frequently identi¢ed, 42% of which were methicillin-resistant Staphylococcus aureus (MRSA). Given the strong association of respiratory tract infections with the development of SAC and BOS, empiric antimicrobial strategies after LTshould include agents directed against GP organisms, especially MRSA.

Transplant Infectious Disease, 2008

Purpose. Clostridium di⁄cile colitis (CDC) is the most common nosocomial infection of the gastroi... more Purpose. Clostridium di⁄cile colitis (CDC) is the most common nosocomial infection of the gastrointestinal tract in patients with recent antibiotic use or hospitalization. Lung transplant recipients receive aggressive antimicrobial therapy postoperatively for treatment and prophylaxis of respiratory infections. This report describes the epidemiology of CDC in lung recipients from a single center and explores possible associations with bronchiolitis obliterans syndrome (BOS), a surrogate marker of chronic rejection. Methods. Patients were divided into those with con¢rmed disease (CDC 1 ) and those without disease (CDC À ) based on positive C. di⁄cile toxin assay. Because of a bimodal distribution in the time to develop CDC, the early postoperative CDC 1 group was analyzed separately from the late postoperative CDC 1 cohort with respect to BOS development. Results. Between 1990 and 2005, 202 consecutive patients underwent 208 lung transplantation procedures. Of these, 15 lung recipients developed 23 episodes of CDC with a median follow-up period of 2.7 years (range, 0^13.6). All patients with con¢rmed disease had at least 1 of the following 3 risk factors: recent antibiotic use, recent hospitalization, or augmentation of steroid dosage. Of the early CDC 1 patients, 100% developed BOS, but only 52% of the late CDC 1 patients developed BOS, either preceding or following infection. Conclusion. CDC developed in 7.4% of lung transplant patients with identi¢ed risk factors, yielding a cumulative incidence of 14.7%. The statistical association of BOS development in early CDC 1 patients suggests a relationship between early infections and future chronic lung rejection.

Solar Physics, 2006

Abstract From the monthly data of cosmic ray intensity (CRI), sunspot numbers (SSN) and solar fla... more Abstract From the monthly data of cosmic ray intensity (CRI), sunspot numbers (SSN) and solar flare index (SFI), an attempt has been made to study the relationship between CRI and solar activity (SA) parameters SSN and SFI. The correlation between SA parameters and ...

Physics of Plasmas, 2006

In modern technological applications electronegative dusty plasmas are widely used in semiconduct... more In modern technological applications electronegative dusty plasmas are widely used in semiconductor materials processing, in development of novel nanomaterials, etc. The dust grains produced by the chemical reaction in gas or plasma-surface interaction in such plasmas can ...

Physics of Plasmas, 2006

... 45, 449 (1997). GLDelzanno and G.Lapenta, “Modified Jeans Instability for Dust Grains in a Pl... more ... 45, 449 (1997). GLDelzanno and G.Lapenta, “Modified Jeans Instability for Dust Grains in a Plasma,” Phys. Rev. Lett. ... Permanent address: Department of Mathematics, Bengal Institute of Technology, Post-Hadia, Kolkata-700150, India. Electronic mail: banamaliroy@yahoo.co.in. ...

Physics of Plasmas, 2004

The effects of nonthermal ions with excess of fast (energetic) ions on linear dust acoustic (DA) ... more The effects of nonthermal ions with excess of fast (energetic) ions on linear dust acoustic (DA) wave propagation has been investigated incorporating the dust charge variation and the isothermal dust pressure variation. It is seen that due to the dust charge variations in the ...

Physics of Plasmas, 2004

The effect of secondary electron emission on dust acoustic wave (DA) propagation has been investi... more The effect of secondary electron emission on dust acoustic wave (DA) propagation has been investigated based on orbit motion limited theory of dust grain charging. The emitted secondaries are assumed to have the same temperature as that of the ambient plasma electrons so ...

Physics of Plasmas, 2010

The effect of magnetic field on the nonlinear growth rate of Rayleigh -Taylor instability induced... more The effect of magnetic field on the nonlinear growth rate of Rayleigh -Taylor instability induced two fluid interfacial structures has been investigated. The magnetic field is assumed to be parallel to the plane of the two fluid interface and acts in a direction perpendicular to the wave vector. If magnetic field is restricted only to either side of the interface the growth rate may be depressed (may almost disappear) or be enhanced depending on whether the magnetic pressure on the interface opposes the instability driving pressure difference g(ρ h − ρ l )y or acts in the same direction. If magnetic field is present on both sides of the two fluid interface, stabilization *

Physics of Plasmas, 2009

The effect of compressibility and of density variation on Rayleigh–Taylor and Richtmyer–Meshkov i... more The effect of compressibility and of density variation on Rayleigh–Taylor and Richtmyer–Meshkov instability of the temporal development of two fluid interfacial structures such as bubbles and spikes have been investigated. It is seen that the velocity of the tip of the bubble or spike ...

Physics of Plasmas, 2011

The combined effect of viscosity and vorticity on the growth rate of the bubble associated with s... more The combined effect of viscosity and vorticity on the growth rate of the bubble associated with single mode Rayleigh -Taylor instability is investigated. It is shown that the effect of viscosity on the motion of the lighter fluid associated with vorticity accumulated inside the bubble due to mass ablation may be such as to reduce the net viscous drag on the bubble exerted by the upper heavier fluid as the former rises through it. *

Physics Letters A, 2007

The effect of secondary electron emission on dust ion acoustic wave (DIA) propagation has been in... more The effect of secondary electron emission on dust ion acoustic wave (DIA) propagation has been investigated based on orbit motion limited (OML) theory of dust grain charging. The emitted secondaries are assumed to have the same temperature of that of the ambient plasma electrons so that the plasma is effectively composed of three components: The ions, electrons and the varying

Physics Letters A, 2000

The effects of nonadiabatic dust charge variation on nonlinear dust ion acoustic waves in collisi... more The effects of nonadiabatic dust charge variation on nonlinear dust ion acoustic waves in collisionless dusty plasma have been studied. Nonadiabaticity generated dissipative effect is found to cause generation of dust ion acoustic shock wave Ž . governed by the Korteweg-de Vries KdV Burger equation. Numerical integration of KdV Burger equation shows that it Ž . Ž . has either oscillatory dispersion dominant case or quasi-monotone dissipation dominant case shock wave solutions. q 2000 Published by Elsevier Science B.V. ) Corresponding 0375-9601r00r$ -see front matter q 2000 Published by Elsevier Science B.V.

Physics Letters A, 2002

Small but finite amplitude nonlinear acoustic mode at high dust density, i.e., the nonlinear dust... more Small but finite amplitude nonlinear acoustic mode at high dust density, i.e., the nonlinear dust electro acoustic (DEA) wave mode has been studied by reductive perturbation technique. The effect of dispersion is introduced to saturate the nonlinear steepening effect leading to Korteweg-de Vries (KdV) equation for the description of its propagation. It is found that the dispersive effect of DEA wave is more pronounced than that of dust acoustic (DA) wave for hydrogen plasma with equal electron, ion temperatures T e and T i . For lower values of T i /T e , the DEA soliton flattens out more and more as the dust space charge density |q d n d | increases but after maximum flattening the soliton width decreases and the soliton becomes more sharply peaked as |q d n d | comes closer to that of ions. In this respect and also in respect of soliton amplitude the behaviours of the DEA wave and DA wave differ qualitatively.  2002 Elsevier Science B.V. All rights reserved. 0375-9601/02/$ -see front matter  2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 5 -9 6 0 1 ( 0 2 ) 0 0 1 9 3 -7

Physica Scripta, 2005

... It is seen that a DIA wave becomes unstable when the ionization rate sufficiently exceeds the... more ... It is seen that a DIA wave becomes unstable when the ionization rate sufficiently exceeds the recombination rate. This is also possible in absence of secondary electron emission. ... Page 4. 300 MR Gupta, Susmita Sarkar, Banamali Roy, Anupam Karmakar and Manoranjan Khan ...